Unit for checking the dosing of pharmaceutical material in a capsule filling machine

ABSTRACT

A unit ( 6 ) for checking the dosing of pharmaceutical material (M) in a capsule filling machine ( 1 ) for the production of capsules (CF) of the type with a capsule lid (C) and a capsule body (F), the machine ( 1 ) comprising a fixed structure ( 15 ) fitted with a rotary drum ( 2 ) for supporting a plurality of capsules (CF) on its edge, opening each capsule (CF) by separating the capsule lid (C) from the capsule body (F), filling the capsule body (F) with a dose of material (M), then closing the capsule body (F) again with the relative capsule lid (C); the rotary drum ( 2 ) having a tank ( 5 ) containing the pharmaceutical material (M) and supporting a plurality of doser elements ( 3 ), each comprising at least one piston ( 8 ) sliding inside a hollow cylinder ( 4 ) to pick up and compress a dose (DS) of material (M) from the tank ( 5 ) and discharge it into a capsule body (F) of a capsule (CF). The unit ( 6 ) comprises sensor means ( 9 ) attached to each piston ( 8 ) for detecting a piston ( 8 ) thrust value (V; V 1 ) on the dose (DS) and transmitter means ( 10 ) connected to the sensor means ( 9 ) for transmitting the value (V; V 1 ) to a receiver element ( 11; 41 ) by the telemetric transmission of a relative signal (S; S 1 ), said receiver element ( 11; 41 ) being fixed on the machine ( 1 ) in at least one zone (P 1 ; P 2 ) of the fixed structure ( 15 ). Power supply means ( 12, 14   a ) are also provided for cyclically activating the sensor means ( 9 ) and the transmitter means ( 10 ) during drum ( 2 ) rotation.

TECHNICAL FIELD

The present invention relates to a unit for checking the dosing ofpharmaceutical material in a production machine.

In particular, the present invention is advantageously applied in acapsule filling machine for the production of hard gelatin capsules forpharmaceutical use, of the type with a capsule lid and a capsule bodycontaining doses of pharmaceutical material in powder or particulateform, to which the present specification refers but without limiting thescope of the invention.

BACKGROUND ART

Generally speaking, a capsule filling machine for the production ofpharmaceutical capsules basically comprises a drum which rotates about avertical axis of rotation, and a circular fixed tank which holds thepharmaceutical material to be fed into the capsules by dosing.

The drum handles and positions the capsules to be filled with thepharmaceutical material by separating the capsule lid from the capsulebody then closing them again once filled. The drum, to which the tankcontaining the material to be dosed is connected, also has a pluralityof doser elements designed to pick up relative doses of material fromthe tank and, respectively, to deposit each dose in the capsule bodybefore the capsule body is closed again with the relative capsule lid.

According to a known dosing method the doser elements, each consistingof a hollow punch, forming a hollow cylinder and housing a piston movingwith alternate motion, perform the following operating steps one afteranother: a vertical stroke by the hollow cylinder into the tank, forimmersion in the pharmaceutical material until the cylinder touches thebottom of the tank, forming a dose or slug of material inside the hollowcylinder; a downward movement by the piston to compress the dose ofpharmaceutical material; a subsequent return upward movement by thehollow cylinder with the compressed dose still inside it, to pick up thedose from the tank; finally, with a downward thrust movement by thepiston, the compressed dose is released into the relative capsule body,after an axial movement designed to align the capsule body on the raisedhollow cylinder, by rotation of the drum.

To correctly pick up the dose then discharge it into the capsule bodybut, above all, to ensure that each capsule contains a dose ofpharmaceutical material whose weight lies within a predetermined weightrange, the vertical stroke of the piston operating inside the hollowcylinder is suitably regulated, in both directions, according to valuesdefined as constants and synchronised with the movement of the hollowcylinder.

To check that the weight of the doses of pharmaceutical material in thecapsules is correct, one known check method involves the use ofprecision scales on which capsules taken as samples from a capsulefilling machine outfeed portion are placed.

Since such scales have high settling times during weighing steps, thismethod cannot be used to check all of the capsules produced by thecapsule filling machine, as this would greatly slow down the productionflow.

To solve the above-mentioned problem, that is to say, to check all ofthe capsules produced without slowing down the production flow, atpresent modern capsule filling machines are fitted with check devicesdesigned to detect the downward force of the pistons during the dosingstep and to control the piston stroke with feedback if said force givesdoses of pharmaceutical material with unacceptable weight values.

In the capsule filling machine described, for example in U.S. Pat. No.6,327,835, each dosing piston of a drum rotating with alternating motionis fitted with a force sensor, connected by connecting cabletransmission systems to a control unit designed to receive, during eachpause in the drum alternating motion, a signal relative to a pistoncompression force value, to compare said value with a predeterminedreference value and to send a feedback signal to adjust the piston driveunit during the pharmaceutical material dosing steps.

The control device described in said U.S. patent is validly used only oncapsule filling machines with alternating motion but, due to theconnecting cable transmission systems, can obviously not be used on acapsule filling machine whose drum rotates continuously at a speed ofrotation which can currently be very high.

DISCLOSURE OF THE INVENTION

The aim of the present invention is, therefore, to overcome theabove-mentioned disadvantages and the problems of the prior art.

In particular, the aim of the present invention is to provide a controlunit which allows an efficient weight check of all of the capsuleproduced by a capsule filling machine, whether it operates withcontinuous or alternating motion.

Accordingly, the present invention provides a unit for checking thedosing of pharmaceutical material in a capsule filling machine for theproduction of capsules of the type with a capsule lid and a capsulebody, the machine comprising a fixed structure fitted with a rotary drumfor supporting a plurality of capsules on its edge, opening each capsuleby separating the capsule lid from the capsule body, filling the capsulebody with a dose of pharmaceutical material, then closing the capsulebody again with the relative capsule lid. The rotary drum has a tankcontaining the pharmaceutical material and supports a plurality of doserelements, each comprising at least one piston sliding inside a hollowcylinder to pick up and compress a dose of material from the tank anddischarge it into a capsule body of a capsule. The unit is characterisedin that it comprises sensor means attached to each piston to detect apiston thrust value on the dose; transmitter means connected to thesensor means for transmitting the value to a receiver element by thetelemetric transmission of a relative signal, said receiver elementbeing fixed on the machine in at least one area of the fixed structure.Power supply means are also provided for cyclically activating thesensor means and the transmitter means during drum rotation.

BRIEF DESCRIPTION OF THE DRAWINGS

The technical features of the present invention, in accordance with theabove-mentioned aims, are set out in the claims herein and theadvantages more clearly illustrated in the detailed description whichfollows, with reference to the accompanying drawings, which illustrate apreferred embodiment of the invention without limiting the scope of theinventive concept, and in which:

FIG. 1 is a schematic top plan view with some parts cut away for greaterclarity, of a capsule filling machine fitted with the unit for checkingthe dosing of material according to the present invention;

FIG. 2 is a side view, partially in cross-section with some parts cutaway, of a portion of the capsule filling machine illustrated in FIG. 1in an operating position;

FIG. 3 is a side view, with some parts cut away and others incross-section, of the capsule filling machine illustrated in FIG. 1 inanother operating position;

FIG. 4 is a flow diagram illustrating the operation of the unit forchecking the dosing of material according to the present invention; and

FIG. 5 is a flow diagram illustrating the operation of a part of theunit illustrated in FIG. 4.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS OF THE INVENTION

With reference to FIGS. 1, 2 and 3, the numeral 1 denotes a capsulefilling machine for the production of capsules CF of the type with acapsule lid C and a capsule body F containing doses of pharmaceuticalmaterial M in powder or particulate form.

The machine 1 basically comprises a drum 2 continuously rotating about avertical axis Z and in a clockwise direction B in FIG. 1, its edgedesigned to support the capsules CF in a known way and to handle andposition the capsules CF at an angle so that they can be filled withdoses of the pharmaceutical material M by separating the capsule lid Cfrom the capsule body F then closing them after filling, with a knownmethod illustrated in FIGS. 2 and 3. The drum 2 is connected to acircular tank 5 containing the pharmaceutical material M supplied to thetank 5 by a material M feed station 100 (FIG. 1).

The drum 2 has a plurality of known doser elements 3, each forming adosing station and designed to pick up doses DS of material M from thetank 5 then deposit each dose DS in the capsule body F of the capsule CFbefore the capsule body F is closed again with the relative capsule lidC.

As illustrated in FIGS. 2 and 3, each doser element 3 comprises a piston8 which moves inside a hollow cylinder 4. It should be noticed that eachdoser 3 preferably comprises a pair of pistons 8 which move insiderespective hollow cylinders 4, but for the sake of simplicity in thisdescription and below reference is only made to a single piston 8 and arelative cylinder 4 without in any way limiting the scope of applicationof the invention.

The cylinder 4 moves vertically in both directions, driven by knowndrive means, not illustrated, between a lowered position (FIG. 2) inwhich the hollow cylinder 4 is immersed in the tank 5, and a raisedposition in which the cylinder 4 is outside the tank 5 (FIG. 3).

The piston 8 is designed to slide vertically inside the cylinder 4,again in both directions, driven by known drive means, not illustrated,in such a way that, in practice, each doser element 3 performs thefollowing operating steps one after another: a vertical stroke into thetank 5 by the hollow cylinder 4 so that it is immersed in thepharmaceutical material M until the cylinder touches the bottom of thetank 5, forming a dose DS or slug of material M inside the hollow 4(FIG. 2); a piston 8 downward movement to compress the dose DS ofpharmaceutical material M (FIG. 2); a subsequent hollow cylinder 4return upward movement with the compressed dose DS of material M stillinside the cylinder 4, to pick up the dose from the tank 5; finally,with a piston 8 downward thrust, release of the compressed dose DS intothe relative capsule body F (FIG. 3) carried by slide means 7 on thedrum 2. In practice, the dose DS of material M to be picked up isdefined by the diameter of the cylinder 4, by the piston 8 initialposition and downward stroke.

As illustrated in FIGS. 1, 2, 4 and 5, the machine 1 comprises a unit 6for checking the dosing of the material M, which in turn comprises, foreach doser element 3, sensor means 9 connected to the piston 8 to detectand save values V relative to the compression force exerted by thepiston 8 on the dose DS inside the hollow cylinder 4, and transmittermeans 10 connected to the sensor means 9 to transmit the compressionforce values V to receiver means 11 by sending relative transmissionsignals S.

The unit 6 also comprises means 12 which supply power to and cyclicallyactivate the sensor means 9 and transmitter means 10 of each doserelement 3.

As illustrated in FIGS. 1 and 5, the power supply and cyclicalactivation means 12 comprise means 13 for activating the transmittermeans 10, one for each doser element 3, positioned on the drum 2, andmeans 14 for supplying power to the activation means 13, positioned on afixed portion 15 of the machine 1.

More specifically, as is better illustrated in FIG. 4, the power supplyand cyclical activation means 12 comprise two stator elements 14 (forexample, permanent magnets), positioned at relative predetermined fixedzones P and P1 of the machine 1, and a rotor element 13 (for example, acoil) connected to each of the doser elements 3. In an embodiment notillustrated, the zones P and P1 coincide, so that there is only onestator element 14.

Each rotor element 13 connected to one of the two stator elements 14together define a transformer assembly for the transfer of electricityfrom the stator element 14 to a single rotor element 13 when they arepositioned close to one another during drum 2 rotation in the directionB.

This transfer of electricity is designed to activate the sensor means 9and the transmitter means 10, to allow, at the zones P and P1, detectionof a value V relative to the piston 8 compression force on the dose DS,subsequently sending the value to the means 10, and, at zone P1 only, asubsequent telemetric transmission by radio frequency of a signal S fromthe transmitter means 10 to the receiver means 11.

Again as illustrated in the diagram in FIG. 4, further power supply andcyclical activation means 14 a comprise a third stator element 14 bpositioned in a third fixed, predetermined zone P2 of the machine 1 toallow activation of a single rotor element 13 positioned on each of thedoser elements 3. The zone P2 corresponds to the part of the machine 1in which each dose DS is discharged into a capsule body F of a capsuleCF.

The third stator element 14 b in the zone P2 is downstream of the othertwo stator elements 14, relative to the direction B of rotation of thedrum 2, which are in the zones P and P1 of the machine 1 fixed structure15.

Moreover, the power supply means 14 a power the transmitter means 10 insuch a way as to allow the telemetric transmission using radio frequencyand by means of a signal S1 to other means 41 of a value V1 relative tothe discharging force required to discharge the dose DS into the capsulebody F.

Looking more closely at the construction details in FIGS. 2 and 5, eachsensor means 9 comprises a pressure transducer or strain gauge 17,preferably a load cell 17 positioned on the upper end of the cylinder 4and connected in a known way to the piston 8. The transmitter means 10comprise a transmission unit 10, for example, a transponder, for thesignals S and S1 connected directly to the load cell 17 and which can besupplied by the rotor element 13 when the latter is activated by thestator element 14 or 14 b.

The receiver means 11 and 41, mounted on the machine 1 fixed structure15, are also connected, for example by a serial cable, to a processingand control device 16 of the type with a microprocessor.

In the preferred embodiment of the invention disclosed, the signals Sand S1 transmitted by the transmitter means 10 to the receiver means 11are electrical signals which are modulated, for example in frequency oramplitude.

In particular, such modulated signals S and S1 are preferably, althoughin a non-restricting way, of the digital type.

For example, the signals S and S1 may be binary and of the known typeOOK, that is, On-Off Keying, preferably at a frequency of 433 MHz.

The signals S and S1 received by the receivers 11 and 41 are then sentin turn to the microprocessor processing device 16, so that the device16 can process the values V and V1 of the compression force on the doseDS and, respectively, of the force for discharging the dose DS into thecapsule body F, comparing them with reference values VF and VF1 saved ina device 16 memory area.

Therefore, in practice, if the value V relative to the piston 8compression force on the dose DS detected by the load cell 17 andtransmitted to the receiver 11 and then to the device 16 is not in linewith the reference value VF with which it is compared, the device 16activates means 30, preferably of the pneumatic type with a pressurisedair jet, to expel the capsule CF whose dose DS was compressed with acompression force with value V, the means 30 being positioned at amachine 1 outfeed portion 31.

If, instead the value V1 relative to the discharging force exceeds thelimit value VF1, the capsule filling machine 1 automatically stops, toavoid the consequent possibility of damage to the cylinder 4 and/or thepiston 8.

Again as illustrated in FIG. 4, the unit 6 also comprises a device 32for manual entry of a weight value to be the predetermined value for thedoses DS of material M which will fill the capsules CF in the machine 1.Similarly, a value VF1 corresponding to a limit force for dischargingthe dose DS into the capsule body F by the piston 8 can also be setmanually.

The device 32 is connected, for example by a serial cable, to themicroprocessor device 16, whose memory contains a special algorithm forconversion of the above-mentioned weight value (for example expressed inmilligrams) into a corresponding thrust force value (for exampleexpressed in Newtons) which must be generated by the pistons 8 and whichwill define the reference values VF and VF1.

The microprocessor device 16 is also connected to a device 33 forweighing the finished capsules CF with a predetermined statisticalcyclicity.

This device 33 is designed to send the microprocessor device 16 a signalSP equivalent to the actual weight of the capsule CF to allowverification through feedback of correct operation of the comparisonsmade by the microprocessor device 16, and therefore, correct operationof the control unit 6.

The microprocessor device 16 also controls a device 34 for generating afeedback signal to adjust the stroke of each piston 8 in the relativehollow cylinder 4, preferably based on a mean evaluation in a givenproduction time interval.

In practice the unit 6 operates as follows.

With the machine 1 stopped, the operator uses the device 32 to set theweight value which will be the predetermined value for the doses DS ofmaterial M that will fill the capsules CF. In this way, the device 16can process the piston 8 compression force reference value VF. Thedischarging force limit value VF1 is set in the same way.

At this point the machine 1 may begin the production cycle and when eachof the doser elements 3, during continuous rotation of the drum 2, iscyclically adjacent to the first stator element 14 fixed in the firstpredetermined zone P the load cell 17 is energised by the rotor 13, inturn activated by the stator 14, and can record the piston 8 compressionforce on the dose DS inside the cylinder 4.

Next, the doser element 3 moves to the second fixed zone P1 in which thesecond stator element 14 is present.

The load cell 17 energised by the rotor 13 sends the value V relative tothe piston 8 compression force previously recorded to the transmitter10, which is also energised by the rotor 13 and transmits the signal Sto the fixed receiver 11 which, in turn, sends the same signal S to themicroprocessor device 16.

In this way, the device 16 can compare the value V sent by means of thesignal S with the reference value VF and make the following choices: ifthe value V lies within the predetermined range set around VF thefinished capsule CF is then fed out of the machine 1 as normal at theportion 31. If the value V is unacceptable relative to the value VF,that is to say, if the value V is not within the predetermined rangearound VF, the device 16 activates the rejection means 30 to expel andreject the capsule CF from the capsule filling machine 1 into a rejectsbin (not illustrated).

Continuous movement of the drum 2 in the direction B then brings thedoser element 3 to the third stator element 14 b positioned in thepredetermined machine 1 zone P2, again activating the load cell 17 torecord the value V1 relative to the discharging force exerted by thepiston 8 on the dose DS during dose DS discharging into the capsule bodyF.

This value V1 is immediately sent by means of the signal S1, from thetransmitter 10 to the fixed receiver 41 and then to the microprocessordevice 16.

The microprocessor device compares it with the reference value VF1previously entered using the device 32, to check that the dischargingforce is correct: if the value V1 is lower than the limit value VF1 theproduction cycle continues. Otherwise, the machine 1 stops to preventbreakage or damage to the cylinder 4 and/or the piston 8.

The microprocessor device 16 is also designed to activate the device 34which adjusts the stroke of the piston 8 whose compression value V wasdetected outside the predetermined range, to adjust the stroke of thepiston 8.

To guarantee the efficiency of the checking system implemented by themicroprocessor device 16, capsules CF considered to be of the correctweight are weighed on the weighing device 33 with a predeterminedstatistical cyclicity.

This device 33 sends a signal SP to the microprocessor device 16equivalent to the actual weight of the capsule CF obtained, so as toverify the correct operation of the comparisons made by the device 16.

In the event of discrepancies between the actual weight and the datasaved by the device 16, the operator may act directly or there may be anautomatic system in the device 16 for correcting the comparison data.

A control unit 6 structured in this way, therefore, achieves the presetaims thanks to an extremely rapid system for checking the dosing of allcapsules produced in the continuous-motion capsule filling machine 1,practically in real time, thanks to the system for radio frequencytransmission of modulated electrical signals, without slowing downcapsule filling machine 1 production at all.

The high speed, precision and flexibility of the system allow its use onall types of continuous-motion capsule filling machines and even onthose with alternating motion, with both high and low production speeds.

The invention described can be subject to modifications and variationswithout thereby departing from the scope of the inventive concept.Moreover, all the details of the invention may be substituted bytechnically equivalent elements.

1. A unit (6) for checking the dosing of pharmaceutical material (M) ina capsule filling machine (1) for the production of capsules (CF) of thetype with a capsule lid (C) and a capsule body (F), the machine (1)comprising a fixed structure (15) fitted with a rotary drum (2) forsupporting a plurality of capsules (CF) on its edge, opening eachcapsule (CF) by separating the capsule lid (C) from the capsule body(F), filling the capsule body (F) with a dose (DS) of material (M), thenclosing the capsule body (F) again with the relative capsule lid (C);the rotary drum (2) having a tank (5) containing the pharmaceuticalmaterial (M) and supporting a plurality of doser elements (3), eachcomprising at least one piston (8) sliding inside a hollow cylinder (4)to pick up and compress a dose (DS) of material (M) from the tank (5)and discharge it into a capsule body (F) of a capsule (CF); the unit (6)being characterised in that it comprises sensor means (9) attached toeach piston (8) for detecting a piston (8) thrust value (V; V1) on thedose (DS); transmitter means (10) connected to the sensor means (9) fortransmitting the value (V; V1) to a receiver element (11; 41) by thetelemetric transmission of a relative signal (S; S1), said receiverelement (11; 41) being fixed on the machine (1) in at least one zone(P1; P2) of the fixed structure (15); there also being power supplymeans (12, 14 a) for cyclically activating the sensor means (9) and thetransmitter means (10) during drum (2) rotation.
 2. The unit accordingto claim 1, characterised in that the signal (S; S1) is transmitted inradio frequency.
 3. The unit according to claim 1 or 2, characterised inthat the signal (S; S1) is a modulated signal.
 4. The unit according toclaim 1, characterised in that the sensor means (9) comprise a load cell(17) connected to each of the pistons (8) for detecting a value (V)relative to the piston (8) compression force on the dose (DS) and forsending a signal (S) to the receiver element (11) through thetransmitter means (10).
 5. The unit according to claim 1, characterisedin that the sensor means (9) comprise a load cell (17) connected to eachof the pistons (8) for detecting a value (V1) relative to the piston (8)discharging force on the dose (DS) while discharging the dose (DS) intothe capsule body (F) and for sending a signal (S1) to the receiverelement (41) through the transmitter means (10).
 6. The unit accordingto claim 1, characterised in that the power supply means (12; 14 a)comprise a stator element (14; 14 b) in a fixed position in at least onezone (P, P1; P2) of the fixed structure (15) and a rotor element (13)attached to each of the rotary drum (2) doser elements (3).
 7. The unitaccording to claim 1, characterised in that it also comprises aprocessing and control device (16) connected to the receiver element(11; 41) and to capsule (CF) rejection means (30); the processing andcontrol device (16) being designed to compare the value (V; V1) receivedfrom the receiver element (11; 41) by means of the signal (S; S1) with arelative reference value (VF; VF1) and to activate the rejection means(30) if the value (V; V1) is unacceptable relative to the referencevalue (VF; VF1).
 8. The unit according to claim 7, characterised in thatit comprises a device (32) for manual data entry, connected to theprocessing and control device (16), for generating the reference value(V1; VF1) in the processing and control device (16).
 9. The unitaccording to claim 7 or 8, characterised in that it also comprises adevice (34) for generating a feedback signal to adjust the stroke ofeach piston (8) in the relative hollow cylinder (4), this device beingcontrolled by the processing and control device (16).
 10. The unitaccording to claim 1, characterised in that it also comprises a device(33) for weighing the capsules (CF), this device being controlled by theprocessing and control device (16).